1. Field of the Invention
The invention relates in general to a chip structure and a process for forming the same. More particularly, the invention relates to a chip structure for improving the resistance-capacitance delay and a forming process thereof.
2. Description of the Related Art
Nowadays, electronic equipment are increasingly used to achieve many various tasks. With the development of electronics technology, miniaturization, multi-function task, and comfort of utilization are among the principle guidelines of electronic product manufacturers. More particularly in semiconductor manufacture process, the semiconductor devices with 0.18 microns have been mass-produced. However, the relatively fine interconnections therein negatively impact the chip. For example, this causes the voltage drop of the buses, the resistance-capacitor delay of the key traces, and noises, etc.
FIG. 1 is a cross-sectional view showing a conventional chip structure with interconnections.
As shown in FIG. 1, a chip structure 100 is provided with a substrate 110, an built-up layer 120 and a passivation layer 130. There are plenty of electric devices 114, such as transistors, on a surface 112 of the substrate 110, wherein the substrate 110 is made of, for example, silicon. The built-up layer 120 provided with a dielectric body 122 and an interconnection scheme 124 is formed on the surface 112 of the substrate 110. The interconnection scheme 124 interlaces inside the dielectric body 122 and is electrically connected to the electric devices 114. Further, the interconnection scheme 124 includes many conductive pads 126 exposed outside the dielectric body 122 and the interconnection scheme 124 can electrically connect with external circuits through the conductive pads 126. The dielectric body 122 is made of, for instance, silicon nitride or silicon oxide. In addition, the passivation layer 130 is deposited on the built-up layer 120, and has many openings respectively exposing the conductive pads 126. The interconnection scheme 124 includes at least one metal layer that can serve as a power bus or a ground bus. The power bus or the ground bus is connected to at least one of the conductive pads 126 through which the power bus or the ground bus can electrically connect with external circuits.
However, as far as the chip structure 100 is concerned, resistance-capacitance (RC) delay is easily generated because the line width of the interconnection scheme 124 is extremely fine, about below 0.3 microns, the thickness of the interconnection scheme 124 is extremely thin, and the dielectric constant of the dielectric body 122 is extremely high, about 4. Therefore, the chip efficiency drops off. In particular, the RC delay even usually occurs with respect to a power bus, a ground bus or other metal lines transmitting common signals. In addition, the production of the interconnection scheme 124 with extremely fine line width is necessarily performed using facilities with high accuracy. This causes production costs to dramatically rise.
The present invention is related to a R.O.C. patent application Ser. No. 88120548, filed Nov. 25, 1999, by M. S. Lin, issued Sep. 1, 2001, now R.O.C. Pat. No. 140721. R.O.C. patent application Ser. No. 88120548 claims the priority of pending U.S. patent application Ser. No. 09/251183 and the subject matter thereof is disclosed in pending U.S. patent application Ser. No. 09/251183. The present invention is related to a R.O.C. patent application Ser. No. 90100176, filed Jan. 4, 2001, by M. S. Lin and J. Y. Lee, now pending. The subject matter of R.O.C. patent application Ser. No. 90100176 is disclosed in pending U.S. patent application Ser. No. 09/691497. The present invention is related to a Japanese patent application Ser. No. 200156759, filed Mar. 1, 2001, by M. S. Lin and J. Y. Lee, now pending. The present invention is related to a European patent application Ser. No. 01480077.5, filed Aug. 27, 2001, by M. S. Lin and J. Y. Lee, now pending. The present invention is related to a Singaporean patent application Ser. No. 200101847-2, filed Mar. 23, 2001, by M. S. Lin and J. Y. Lee, now pending. Japanese patent application Ser. No. 200156759, European patent application Ser. No. 01480077.5, and Singaporean patent application Ser. No. 200101847-2 claim the priority of pending U.S. patent application Ser. No. 09/691497 and the subject matter of them is disclosed in pending U.S. patent application Ser. No. 09/691497.